Russia’s Sputnik V vaccine was 91.6% effective against COVID-19 disease in a late-stage trial, according to new interim results. The results come in stark contrast to messaging from U.S. health officials, including Dr. Anthony Fauci, who sowed serious doubt over the jab after it was rolled out in Russia ahead of advanced studies on safety and efficacy.
The findings, published in The Lancet on Tuesday, drew from a double-blind trial across 25 sites in Moscow, and revealed a 91.6% efficacy against COVID-19 disease 21 days after the first dose, and 100% effectiveness against moderate-to-severe COVID-19 disease among some 19,800 adult participants.
“Our interim analysis of this phase 3 trial of Gam-COVID-Vac has shown promising results,” study authors wrote, later writing, “Our interim analysis of the randomised, controlled, phase 3 trial of Gam-COVID-Vac in Russia has shown high efficacy, immunogenicity, and a good tolerability profile in participants aged 18 years or older.”
Study co-leads included Denis Logunov and Dr. Inna Dolzhikova, who are affiliated with The Gamaleya Center in Moscow.
The team of Russian researchers derived vaccine efficacy results from 78 cases of COVID-19 that cropped up among all trial participants three weeks after the first dose.
“From 21 days after the first dose of vaccine (the day of dose 2), 16 (0.1%) of 14,964 participants in the vaccine group and 62 (1.3%) of 4,902 in the placebo group were confirmed to have COVID-19; vaccine efficacy was 91.6%,” study authors wrote.
After at least 21 days from the initial dose, there were no cases of moderate-to-severe COVID-19 in the vaccine group, but 20 cases arose in the placebo group, translating to 100% vaccine efficacy against more serious courses of disease.
Researchers suggested the two-dose recombinant adenovirus vaccine induced an immune response, including among older adults, and was well tolerated; 45 (0.3%) of 16,427 vaccinated participants and 23 (0.4%) of 5,435 people given the placebo had serious adverse events, but these serious side effects were not considered vaccine-related.
The most common side effects were “flu-like illness, injection site reactions, headache” and weakness, per the study.
There were also four deaths reported among trial participants, (three in the vaccine group) but none were found to be associated with the vaccine. Among the vaccine group, two deaths were tied to COVID-19; “these two participants were probably already infected with SARS-CoV-2 at the time of randomisation and vaccination,” study authors wrote. The other death involved a spine fracture. The death in the placebo group involved a hemorrhagic stroke.
Several unknowns remain, like duration of protection, and how well the vaccine works in teenagers, children and pregnant women.
Of note, the sweeping majority of trial participants were white, and the Russian researchers said they “welcome further investigation in a more diverse cohort.”
Finally, the team noted that, as of Jan. 23, over 2 million doses of the Sputnik V vaccine have already been administered to the public in Russia, mostly in high-risk populations, and essential workers like health care personnel and educators.
“The phase 1/2 clinical trials of the vaccine were completed in August, 2020,” study authors wrote. “The results showed that the vaccine was well tolerated and highly immunogenic in healthy participants. As a result, the vaccine candidate was provisionally approved in Russia according to national legislation.”
Researchers are also looking into a single-dose regimen of the vaccine.
The vaccine efficacy results exceed those recently announced by Johnson & Johnson, which saw its single-shot coronavirus vaccine reveal 66% efficacy in preventing moderate-to-severe COVID-19 in a global trial. However, mRNA vaccines developed by Pfizer-BioNTech and Moderna are 95% and 94.5% effective against COVID-19 disease, respectively.